Pulse type multiplex communication system



April 20, A1954 c; w. HANSELL v 2,676,301 PULSE TYPE Mun-TIMEX comwurcuzon sym original Filed May 28, 1949. 4 2 sneets-snae 1 ATTORNEY April 2o, 1954 c.' w. HANsr-:LL ,2,676,301 PULSE TYPE MULTIPLEX .COMMUNICATION SYSTEM original Filed may 2,8, 1949 2 Sheets-'Sheet 2 INVENTOR Yazegce W15/anse!! ATTORNEY Patented Apr. 20, 1954 UNITED srlvri:s PATENT oi-Flcs P ULsE TYPE MULTIPLEX COMMUNICATION SYSTEM 'Clarence 'W. HanselL Port Jefferson, N. Y., assignor to Radio Corporation of America, a 'corporation of Delaware yApplitman MayV 2s, 1949,

.serial No. 96,124, now

Patent N0. 2,640,921, dated June 2, 1953, which Vis a division of September4, 1951,

application July 17, 1943, :now Patent No. August 16, 1949. Divided and Serial No. 245,036

1a claims. (o1. 332-9) The invention relates tol communication .sys-

. pucation serial No. 495,181, nieu'. 1.7 July 1943,

issued AAugust 16,1949, .fas U; S. Patent 2,e78,919. .In copendng application, .Serial No. 371,865,

Vfiled `December ,27, .1941), now -U. S. Patent 2,381,4i4, .issued 7i August 1945, there .is disclosed Ya pulse `type communication system in which the receiver ,is rendered Iopznlative solely at time periods when the signal pulses are -due 'l to arrive. `Such a rreceiveroperatedinthis manner-is preferably termed a ,shutteredor gated .receiver.

The advantages of such .asystein :are: (l)V rlhe peak .power at the transmitter Acan :be lmade vto exceed considerably that which isobtainable in .a A continuous wave system, by vvirtue :of the fact that the transmitted power is concentrated in the short -pulsessand 2) that there isobtainaloleV lan increase =in Sthe signal-to-nose power com- ;pared to continuous wave systems, not only-beti-me periods lwhich .-mayf-be occupied ,'bythetransmitted pulses, :thuseliminating thefeiiect of noise and 4interference occurring vbetween pulses. v

-In Iaccordance ,withfthe inuentionthere is Dro- -vided va multiplex system wherein la multiplicityY of transmitting channels are operated over a rsingle transmitter to transmit .non-,overlapping fpulses ,which are very short compared Vto thetme intervals between them. The train "or group fof Jpulses from each transmitting station ihas Aits Vown modulation impressed thereon,v and the pulses from all vtransmitting stationsoccupy only L and is .thus high .compared .to known..-oontinu ous i.

:wave systems.l At the receiver, a synchronization systemv is employed. `to enable .the .di'ilerent re- 'ceivers .or utilization .circuitsto be ,individually responsive atdiiterent times and solely at those times at whihjtheesignal .pulsesareduejto arcause-of the increased ltransmitted lpowerbut also Y r,because the :receiver is responsive only during Serial No. 495,181, 2,478,919, dated this .application Tive. Thresholding and limiting devices may be employed at the receiver to further reduce the noise. Thusif-there are continuous wave transmitters which might tend to interfere with the pulsing system of the invention, the output 'from `the .continuous vwave transmitters `*must reach the receiver of the invention with lgreater "strength to produce interference than with -a continuous wave receiver. S0 vlong as the receivedY strength of *the continuous Waves :is less .than the -threshold -value set at the receiver of the-invention, the continuous AWaves will not interfere lgreatlyrwith the Voperation of the present invention. Likewise, if the continuous waves do not Ymodulate Ithe signal current down to z values'below the-limiting value they will not interfere greatly with the operation of the present invention. 'In general, so long as the peak amplitude of Vall noise'and interference combined is less than half the peak amplitude 0f the pulse signal, a very vgreat reduction in the effect of the combined-noise and interference may be -accomplished-bygthe thresholding and limiting.

In accordance with the invention, all pulse transmitting stations 'of .the Amultiplex system 4operate from :a single transmitter `and have the lsame pulse or repetition rate, although the different trains `or groups of pulses from the stations `occupy separate time periods. Eachchannelof the transmittercontains the necessary components for modulating the pulses in either` ytime phaseor. width of the `pulse inresponse to applied signal voltages; According to the .invention a pulse delayer circuit is utilized 'to control the times at which the edges of the pulses are formed. In one arrangement the time displacement of both 'leading and trailing edges ofthe pulses are proportional to the applied modulating signal voltage and in the other the timing of the leading edge of the pulses is maintained at 'fixed rate while the timing ofthe trailing edges with respect to that of the leading edges is made proportional to themodulating signal voltages.

A more detailed description of the invention will now be given with Vreference to the accompanying draw-ing, forming `a part of the specication and Yin which:

Fig.V -1 schematically illustrates the transmit- Fig. 2 schematically illustrates details of a [pulse delayer circuit which can be used in the transmitting system shown in Fig. 1 and which isusedas a basis for explaining the operation of pulse width modulators according to the invention; and

Figs. 3 and 4 schematically illustrate details of diierent types of pulse Width modulation circuits which can be used in the transmitting systern of Fig. 1.

Referring to Fig. 1, the e is shown in block diagram a pulse type multiplex transmitter suitable ior the transmission of pulses which are modulated in length or timing. This transmitter' includes a pulse keyed radio frequency amplier I which is supplied with radio frequency excitation from a constant frequency oscillator Il. Transmitter I0 is provided with vacuumk tube keying equipment capable oi causing the transmission of very short pulses in response to short input pulses. The output from the transmitter l0 passes over a suitable transmission line I2 to an antenna system I3, here shown, by way of example only, as a directive antenna in the form of a parabolic reflector having a dipole Vat its focus. A pulse oscillator I4 produces pulses at a constant rate, which pulses are short compared with the time spacing between them.

These pulses are repeated at a frequency above the highest modulation frequency, and are delivered to pulse modulators I5, I6, I1, etc. and to a pulse delayer 20. The pulse modulators I5, IE, and I'I have respectively impressed thereon modulation inputs from leads I', I6' and I1', in order that the outputs of these modulators consist of trains or groups of pulses suitably moduylated in accordance with the intelligence to be conveyed on the different channels. The outputs from the pulse modulators I5, I6, I1, etc.

are respectively deliverel to pulse delayers and keyers 2l, '22, 23, and so on. These pulse delayers are adjusted for different delays in order to provide pulses which constitute the input to the transmitter or pulse'keyed radio `frequency ampliiier I0. The pulses delivered to the' transmitter I0 fromV the delayer circuits arepreferably equally spaced in time, on the average, and recur at a pulsing rate equal to the rate of the pulse oscillator I4 multiplied by the number of pulse delayer modulators. Obviously, the pulse outputs from the different channels, each of which includes a pulse modulator and delayer circuit, are independently modulated for the transmission of independent programs or modulations.

The pulse delayer circuits 202I, 22, 23, and so on pass pulses at the same repetition rate as the pulse oscillator I4 but at different times. Thus, if the pulse modulator circuits modulate the length of the pulses, for example, the transmitter will send out constant frequency but variable length pulses separated in time. If, however, the pulse modulators modulate the timlng of the pulses, the transmitter I0 will send out timing modulated pulses whose average frequency is the .same but which are retarded or advanced in time by the modulation. L

The pulses from each delayer circuitvare short compared to the time intervals between them, in order that the pulses from all the channels 4occupy only a small percentage of the total time for all conditions of modulation. Thuskas an example, a 5 channel telephone multiplex system including a synchronizing channel might have a pulse rate in each channel of 10,000 per second, in which case the average spacing between centers of continued pulses Will be 20 micro-seconds. The pulse length may be on the order of a half micro-second. For this example.`V- it will be evident that the percentage of time occupied by all pulses in each cycle of operations for all conditions oi modulation may vbe only 2.5 percent of the total elapsed time, as measured from the beginning of one pulse transmitted by the iirst channel to the beginning of the next pulse transmittecl from the same channel in one complete cycle of operations. With this percentage of operating time the transmitter I0 can provide on the order of 40 times as much peak power as can be obtained from a continuous wave transmitter of equal size and cost.

It should be noted that the pulse oscillator I4 impresses its output directly upon the pulse delayer and keyer 20 without the intermediary of a pulse modulator circuit. This arrangement is preferred because it is desired that the pulses from the output of the pulse delayer 20 be the first one received at the receiver, and these pulses employed to synchronize or render operative the various receiving circuits solely'at those time periods when the signal pulses for the respective channels are due to arrive. In view of the slight delay occasioned in the system of the invention in rendering the receiving circuits sequentially operative after the receipt of the i-lrst pulse, it is preferred that there be no modulation impressed on the synchronizing pulses, in accordance with the preferred embodiment of the present invention.

Referring to Fig. 2 in more detail, there is shown a tetrode vacuum tube 30 to whose control grid is supplied an'input pulse through a transformer 3l. A positive polarizing potential is supplied to the anode of the vacuum tube through a variable resistor 32 and the primary Winding of a transformer 33. A capacitor 31?. is connected between the cathode of the tetrode and the junction between the lresistor 32 and the primary Winding'of the'transformer 33. In circuit with the cathode as shown, there is provided a capacitor 35 which is shunted by a resistor 36, the time constant of which network` determines the time of delay. Resistor 35 is preierably adjustable in order to accurately set the delay desired between the input pulse and the output pulse. The time delayed output pulse is taken from the secondary winding of the transformer 33. Vacuum tube 30 is so biased that it is normally conducting (that is, anode current flows in the absence of an input pulse). In this condition, a current will flow from the positive polarizing source through the resistor 32 and through the primary winding of transformer 33, thus shunting or lay-passing capacitor 34. An incoming pulse applied to the transformer 3| will drive the grid of the tetrode momentarily positive to charge the capacitor 35, due to grid rectication, as a result of which 'a negative charge is placed on the grid of the tube 30', thus biasing v the tube to euto. When the tube 30' is non-conducting, current will flow from the positive anode polarizing source through the capacitor 34 to ground, and will thus charge the capacitor 34. When the charge on capacitor 35 leaks off through its shunt connected resistor 36, the grid will approach a state of zero potential relative to the cathode, at which time the tube 30 will pass current, thus enabling the capacitor 34 to discharge across the tube. A pulse is thus passed through the transformer 33 whose time of occurrence is controlled by the adjustment of the grid resistor 36, the resistance value of the latter `determining the length Of time it takes for the-charge on capaci amc-,co1

5, tor-35: to'leak. oi. The rateof' repetition of the pulses across the transformer 33 is, of course, determined1 byv the repetition rate of the input pulses. The period' of discharge of the capacitor 35 should be less than the time spacing between the incoming. pulses; to which the output pulses are responsive, and should correspond to the relative time delay desired. in pulse delayer and keyer units 2U, 2t, 22 and 23 of Fig. 1. A

resistor 32' and-a capacitor 34" are in. the screen gridcircuit of tube 3Q'. Both capacitors 34 and 34' charge anddischarge simultaneously, thus providing a sharper output pulse from the transformer 33 than would be obtainable with a triode circuit which would notv include capacitor 34'. It should ybe noted that capacitors 34 and 34 are connected to the positive polarizing. 'potential through separate resistors: 32 and 32', respectively- Fig. 3 shows a pulse modulation circuit which canbe employed-inthesystem of-F-ig; 1 for modulating the time of. the pulses. This circuit includes a pulsev delayer andA pulse timing modulator. Referring to Fig. 3 in more detail, there is shown a triode vacuumk tube 50 across whose grid and cathode are connected a circuit 5i which extends to thepulseoscillator M of Fig. l, and also a modulation input circuit 52 whichl extends to the sourcevof modulatingpotentials for impressing modulationson the pulses in accord- -ance with the intelligence tobe conveyed. The Amodulation input circuit` 52 is connected to the Agrid and cathode of theA triodev 58 through an Aaudio frequency transformer. 53. In eiiiect,v the vacuum tube 5D is ay pulse amplifier as well as a pulse modulator and a pulse limiter. The anode vcircuit of triode 50 includesy anv inductance 54 ywhich stores energy therein; vhichenergy is 'controlled by the tube: anode currentfor delivery to the pulse delayer and pulse timing modulator vacuum tube 3G'. The control grid of vacuum tube 33 is connected tothe-anode of the vacuum tube 50; througha capacitor 5-6. A- capacitor 34 is'connected between the cathode and anode of the pulse delayer` 30', while al capacitor 34 is connected between the screen grid and cathode of tube 30 in substantially the same manner as the same numbered elements of Fig. 2. It Ishould be noted that the capacitors 34 and 34 have individual resistors 32 andv 32 connected between them and the positive anode polarizingr potential. An adjustable resistor 5l is connected between the cathode and-control grid of tube 36 for providing an adjustment of average pulse delay.

In the operation ofthe circuit shown in- Fig. 3, the triode 5u is normally conductive and energy -is stored in inductor4 54. When a negative pulse fromthefoscillator M4 is applied to theoircuitjgi and thence to the. grid of the triodeythe tube 53 will be cut off. anda positive'pulse appliedto the controll grid ofthe tetrode 33'. The tetrode 3D is normally conductive in the; absenceof pulses. The application of' apositive pulseto-the control gridf of the tetrode 3S. will cause grid rectification which will charge capacitor 53 negatively on the side adjacent thecontrol grid of the tetrode 39. The tube 33 is-thus leftinan anode current cut-onf; condition. During, this condition, the capacitors 3l! and 34- will: be charged and both of' these. capacitors will discharge through the tube-.30 when;` the negative charge ony capacitor vdleaksxoff. The operationof vacuum` tube 3,0", 'it will thusbe seen, is substantiallv,A similarto the operationof the arrangementv shown-in Fig. 2,

6. previously described'. For modulation purposes', the' input to the triode 50 through circuit 521 andv transformer 43- will vary the average bias of the triode amplifier and in this4 manner vary the energy stored in inductor L andthe strength of the pulse delivered to the tetrode, as a result of which the peak charge on capacitor V56 will be .varied inr accordance with the modulation, thus varying the time delay of the output pulse relative to the inputV pulse. It should be noted that the energy stored in coil 54 is delivered to the delayer tube 30' at each pulse. The anode current in the tube 50 should, of course, reach a substantially steady state value before each pulse. If desired, there may be provided a feedback regenerativev circuit in the tetrode circuit or in a later stage to sharpen the output pulse;

The system of Fig; 4 shows a pulse modulation circuit which may be'- used in the system of Fig. 1 for modulating the length or width of the pulses. This circuitshown inl Fig. 4, like that shown in Fig. 3i-nc1udes'both the pulse modulator and the pulse delayer. The elements appearing in Fig. 4- which correspond in function to those in Fig. 3 have been given the*v same reference numerals. In addition, the .system of Fig. 4 includes a pulse peaklimiter tube 32 which follows thepulse delayer and modulator 30' in order to convert variable amplitude pulses from the output of the `delayer tube to variable length or variable widthpulses. TheI pulse4 delayerY and length modulator herein represented by Vacuum` tube tetrode 30, with itsfassociated elements, is substantially the same asithat shown in Fig. 3. It

' should' be noted that in Fig; 4 the pulse input circuit 5| is'appliedbetween the grid'and cathode of pulse amplifier tetrodevacuum tuber 60. The screenv gridv andcathode of tube GS are connected together through af by-pass capacitor 54, in turn shunting aV4 portion-of. a potentiometer circuit 65. The modulation inputcircuit 52, however, is ap'- plied in Fig. itcV atransformer 3|', which is connected in such manner that the anode supply voltage of tetrode 33 is modulated in onev sense While. the control grid-cathode potential of tube 30' is modulated inl an opposite sense for the purpose of balancingpthe eect of the modulation upon the time delay. 'Ifhus pulsesvof variable amplitude are; obtained from the delayer tube 30', which after being limited in pulse peak limitertube 62 appear'as pulses of variable length or width inthe output circuit. 63. The pulse amplifier and limiter tube tu is normally con- Vductive in they absence of anegative input pulse from the oscillator |4 applied tc-circuit 5l. The application of a negativepulse tothe circuit 5i serves; to. cut off the anodeY current in tube 60 momentarily, as a result of which a positive .pulse is;delivered into thefdelayer tube 30 to producegrid rectification;

Details of multiplex receiving systems for use inreceiving. the multiplicity of short duration pulses of received energy sent out by the multiplex transmitter of` Fig. 1 incorporating the circuit arrangements shown in Figs. 2, 3 and 4 may be had as reference to parentlU. S. application Serial'No. 495,181,1iled'July 17,1943, and issued August 16, 1949, as U. S; Patent 2,478,919.

The invention claimed is:

l. A pulsedelay circuit' comprising-an electric tube having' a cathode, a signall grid, a further grid and'ananode, an input circuit connected between sa-id signal grid and` said cathode, said input circuit includinga capacitive-elementrmseriesthere with.. af resistor shunted across said signal grid andsaid cathode, a pair ofresistors connected in series between said anode and the positive terminal'oi a source of unidirectional polarizing potential, the constants of said circuit being such that said tube normally passes anode current in the absence of a pulse applied to ksaid input circuit, a capacitor connected between the junction of said pair of resistorsv and said cathode, a further capacitor connected between said cathode and said screen grid, anda resistive connection between said screen grid and the positive terminal of said source, whereby the application of a pulse to said input circuit charges said capacitive element to bias said tube to cut-off, thereby permitting a'charge to build up on said capacitors, said capacitors discharging across said tube when the charge on said capacitive element leaks ofi, as a consequence of which an output pulse is produced at the anode of saidtube.

A2. A pulse translating circuit arrangement `including an electron discharge system having at least a cathode, a control grid. a further grid and an anode, serially connected resistors connected to said anode, a capacitor connectedbetween the junction of said serially connected resistors and said cathode, a resistance element connected to said further grid, a capacitive element connected between said further grid and said cathode, a resistive element coupled between said control grid and said cathode, the resistance value of said element determining the amount of delay between a pulse applied to said control grid and the appearance of 'a corresponding pulse at said anode, a pulse input circuit comprising an electron discharge device havingcathode, control screen and anode electrodes,A an inductor connected to the anode electrode 'to store energy therein in response to pulses applied to said control electrode, a capacitor inter-icou'pling said anode electrode and said control 'grid to apply pulses of energy to the latter in accordance with the energy stored in said inductor.

3. A pulse modulator circuit arrangement including an electron discharge system vhaving at least a cathode, a control grid, a further grid and an anode, serially connected resistors connected to` said anode, a capacitor connected between the junction of said serially connected resisters and said cathode, a resistance element connected to said further grid, a capacitive element connected between said further grid and said cathode, a resistive element coupled between said control grid and said cathode, the resistance value of said element determining the amount of delay between the pulse applied to said control grid Iand the appearance of a correspondingr pulse at said anode, a pulse input circuitcom'- prising an electron discharge device havingl cathode, control screen and anode'electrodes, an inductorl connected to the anode electrode to store 'energy therein in response to pulses applied to said control electrode, a capacitor inter-coupling said anode electrode and said control grid of said electrode discharge system to apply pulses of energy to the latter in accordance with the energy stored in said inductor, a bias circuit connected to said control electrode of said electrode discharge device, and an element interposed in said bias circuit to apply modulating potentials to said control electrode to vary the amount of energy stored in said inductor in accordance with the applied modulating potential, thereby to produce a pulse at said anode of saidelectron disjcharge systemvarying ,in time with respect' to the pulse appliedr to said grid electrode of 'said electron discharge device.

e. A pulse delay circuit comprising an electric tube having a cathode, a signal grid, a further grid and an anode, lan input circuit connected between said signal grid and said cathode, said input circuit including a capacitive element in series therewith, a variable resistor shunted across said signal grid and said cathode, a pair of resistors connected in series between said anode and the positive terminal of a source of unidirectional polarizing potential, the contents of said circuit being such that said tube normally passes anode current in the absence of a pulse applied to said input circuit, a capacitor connected between the junction of said pair of resistors and said cathode, a further capacitor connected between said cathode and said further grid, and a resistive connection between lsaid further grid and the positive terminal of said source, whereby the application of Va pulse to said input circuit charges said capacitive element to biassaid tube to cut-01T, thereby permitting a charge to build up on said capacitors, said capacitors discharging across said tube when the charge on said capaci tive element leaks off, as a consequence of which an output pulse is produced at the anode of said tube, the amount of delay between said input and said output pulse being adjusted by operation of said variable resistor.

5. A pulse energy translating circuit comprising a vacuum tube having anode, cathode, signal grid and further grid electrodes, a capacitor connected between the further grid and the cathode, a direct connection from said cathode to a point of reference potential, a pair of serially arranged resistors connected between -said anode and a source of unidirectional potential, a capacitor connected between the junction point of said pair of impedances and said cathode, a circuit including a series capacitor and a variable shunt resistor for applying input pulses between said control grid and cathode, an output circuit coupled to said anode for deriving time delayed pulses, and means to apply modulating potentials to said input circuit to vary the energy of said pulses in accordance with the modulating potential.

6. A pulse translating circuit including a controlled electronl flow system having at least two electrodes dening an electron path the first one of said electrodes being an output electrode, and the second being connected to a point of fixed potential and a third electrode associated with said two electrodes to control the flow of electrons in said path," an output load impedance element connected to said output electrode, a storage capacitor coupled in series circuit relationship with said load impedance element and said electron iiow paths, a 'pulse input circuit having a series capacitor therein and a resistive element coupled between said third electrode and said point of ixed reference potential, said circuit having constants at which the electron flow in said system is of one nature, whereby the application 'of a pulse to said input circuit renders the electron iiow of opposite nature to charge said storage capacitor and said series capacitor, said storage capacitorv discharging over said electron path when the charge on said series capacitor leaks ofi thereby producingan output pulse at said load impedance element, and a modulation input circuit separate and apart from said pulse input circuit .and coupled across at least part of said resistive element to apply modulat- 9 ing potentials to wary ithe time fof :charge :and discharge vo'f said :storage capacitor in 4accordance with Ithe v.amplitude tof said modulating potentials. Y

7. A pulse ltime modulatingbcircuit including a controlled electron liiow system fhaving .at .least two electrodesdeiningan electron .path theirst one of said 'electrodes .bei-ng an output electrode, and vthe second being :connected .to V.a 'point 'of fixed potential *and a vthird 'electrode associated with said `Atwo :electrodes 'to control the flow `of electrons in said path, .an `outputflcad impedance element connected Lto said output jelectrode, a storage capacitor coupled fin :series 4circuit .relationship said load fimpedance .element and said electron flow :.pa'ths, a pulse yinput vcircuit having a series :capacitorfand fa shunt resistor .therein coupled between said third :electrode and .said point of x'ed .reference potential, .said .circuit having constants :at which .the electron :flow in said system is of one nature, wherebythei'applicationoi-.a pulse to said inputcircuitrenders-the electron ow .of opposite -nature tocharge said. stkiragev capacitor and said: series capacitor, said storage capacitor discharging over .said electron path when the .charge-1011 saidseries l.capacitor leaks oiftherebyiproducing. 'anoutputpulselat said load impedanceel'ement, a :controlled electron flow device lliaving atfleastitwoelectrodes denningan electronpath .anda lfurtherelectrodeass'ociated with said two electrodes .to .control fthe dw of-electrons'inrsaid path, .said device A.being coupled lto said pulse input circuit, an inductor coupled to :said device vtoi-store energy under. control of :pulses 'applied :to said `further electrode, and means `to apply" modulating Ypotential to said furtlier.V electrode to wary .the :energy vstored .in said inductor `to vary =th'e .charge'and discharge of .said .storage capacitor in accordance with the amplitude of .said modulating. potential.

8.A pulse-.delay and modulator circuitcomprising an electron discharge :device .having a cathode, -..a signal-.grida -furthergrid,"and an anode, an input circuit Iconnected between said signal :grid and said cathode, fsaidiinpu't .circuit including a capacitor connected inseriesvtherewith anda .shunt-resistor; a pairf of..ir'esis`tors 4connected 1in series between' said:l anode'an'dttheipositive :terminal ofa .source of unidirectionalJ polarizing potential,v the `constants ofi-said circuitfbeing suchvthat said tube "normally .passes anode current in the .absence-.of a pulse applied to -said inputeircuit, a furthercapacitor@connected betweenf said .cathode and said further lgrid, 'and a resistive connection between "said l"further Tvgrid and thezpositive7 terminaly of '.-said source; yanother capacitor connected between .said cathode @and the junction vof .said serially connected resistor, whereby the application .of a pulseto saidinput circuit charges -said rst capacitor to fbias l"said tube to .cut-01T, therebyipermitting vcharges T'to build uponlboth of said Asecond-and'tfhirdca? pacitors, said last capacitorsdischargingthrough; said tube 1 when `the charge4 on the first capacitor leaks 'offgasa consequence 'of which'anoutput pulse is produced at said anode.' and' means "to app-ly'rnodulating potentials'l to saidinput circuit to vary the .constantsoflsaid .circuitjthereby to vary the time delay between the application .of a. pulse to v.the input circuit .and the .production of the correspondingv output ,pulse atfsaid anode.

.9@ .A .pulse -delay -andy modulator scircuit .comprising fan yelectron .discharge :device ..having .a cathode, :a 4signal afgrid, ya further sgrid, #andY ian Bil ' to vary .the .width lof. :said

resistors connecting anode. anl input 'circuit lconnected between said signal grid and 'said cathode, said input circuit including a capacitor connected in series therewith anda shunt resistor, apair of `resistors connected in series between-said anode and the positive terminal of asource of unidirectional .polarizing potentiaLthe constants ofasaid circuit being such that said .tube `normally passes anode `currentrfin' the absence of apulse .applied tosaid input circuit, a further capacitor connected between "said cathode and said further grid, and a resistive connection between said furthergrid and the ,positive terminal .of .said source,.another capacitor connected between said cathode and the junction of said serially connected resistor. whereby the application of .apulse to said input circuit-charges said rst .capacitor to bias said tube tocut-oi, thereby permitting charges yto build ,up on `both said second and vthird Acapacitois,y said lastxcapacitors .discharging through said tube rwhenvthe charge on .the first .capacitor leaks oi, asiazconsequencezof which anfoute putcpulse is produced at-.said anode, and'means to .apply Amodulatingpotentials :to said. input-.circuit to vary .the-constantsof. said circuit,-thereby to vary the time delay between theapplication of ra .pulse to theinput.circuitLand .the prdouction of the .corresponding .output .pulseatfsaid anode and athe amplitude :of said pulses,..and:.a pulse peak limiter circuit coupled to said anode output pulsein proportion Ltothe .amplitude thereof, said circuitcomprisin'g. fan V.electron Idischarge structure having cathode, signal, .further and .anode electrodes, saidsourceiof unidirectionall to said .f anode `and further and acapacitor connected polarizing v.potential electrodes, ra :resistor inparallel betweensaid further andsaid cathode electrodes, Land :a capacitor .coupling said signal electrode Ito :the anode ofsaidv electron dis charge device..

10. -Acpulsedelay circuitfrcomprisng an electric tubejhaving a cathode, :a ,signal -grid,..a further grid andan anode, an Vinput .circuit connected between said signal grid vand said ..cathode.said input ,circuit including 'a :capacitive .element .in series therewith, a vgrid, resistor and .a .tapped resistorV connected in .-serieslandlshunted across said signal, vgrid 4 and -said .cathode Ywith uthe tap of `the latter v.connected .to .said cathode, .a pair of resistors connected in series between .said anode and the positive .terminal .of `a :source `of unidirectional polarizing-potential, `the vconstants of. saidl circuit-.being-.such that saidy tube. normallsr passes anodecurrent in the absence ofapulse appliedto said input circuit,.avcapacitor connected between .the junction of said pair of resistors and said cathode, a further capacitor connected. between Asaid .cathode :andsaid screen grid, and a resistive connection between said vscreen grid and thepositive terminalofsaid source, whereby the applicationiof a pulse -to said input circuit charges said .capacitiveelernent to bias said tube .to cut-off, thereby .permitting a charge to build up on said capacitors, said capacitors `dischanging v.across said tube when the charge on said vcapacitive elementleaks off, as a consequence v.of which an output pulse isvr produced at the anode vof :said .tube, `a 4transformer having the vsecozfidarywinding thereof connected across saidatappedresistor, anda capacitor coupling :the end of saidftappedresistor remote from saidgrid resistor .Sto .the tendiof 4.said ;series:icon.

nectedr resistors :remoteafrom said anode.

11. A pulse modulator `.circuit arrangement 11` having input and output circuits and including an electron discharge system having cathode, grid, input control and output anode electrodes, and electrode intercoupling capacitors and resistors arranged to produce a pulse in said output circuit in response to a pulse applied to said input circuit, means to modify said pulses, said means including means to derive modulating voltages oi opposite sense, means to apply one of said modulating voltages to said input circuit, and means .to apply the other oi said modulating voltages to said output circuit whereby the eiiect of 'said modulation voltages on the timing of said output pulses is substantially balanced. l 12. Apulse regenerating circuit having input and output terminals, an output pulse being produced at said output terminals in response to a pulse applied to said input terminals, means to apply modulating potentials .to said pulse regenerating circuit to modify said output pulse with respect to said applied pulse, said means comprising means to derive modulating currents of opposite sense, means to apply one o said modulating currents in one portion of said pulse regenerating circuit, and means to apply the other of said modulating currents to another portion oi said circuit whereby any deleterious eiiects of said modulating potentials on the Vregeneration oi said pulse is substantially elimif. nated.

13. A pulse modulator.. .circuit arrangement having input and an electron discharge system having cathode, grid, input control and output anode electrodes, and electrode intercoupling capacitors and resisters arranged to produce a pulse in said output circuit in response to a pulse applied to said input circuit, means to modify said pulses, said means including means to .derive modulating Voltagesof opposite sense, means to. apply onek of said modulating voltages to said input circuit, and means to apply the other of said modulating voltages to said output circuit, said modulating voltages having amplitudes diieringin propor.

tion to the voltage levels of. said input and said output circuits, whereby the individual effects oi said modulation voltages onthe timing ci said output pulses is substantially balanced.` f

14. A pulse Width modulation circuit including an electron discharge .system having atleast cathode, control, and anode electrodes, said cathode being at a point of fixed reference po ten'tial, an output load impedance element connected to said anode electrode', a storage capaci` tor connected to said cathode electrode and to said load impedance elcmentremote from said anode electrode, a control capacitor coupled to' said control electrode, an electron discharge system for applying pulses to said circuit between said control capacitor and said point of tion potential winding, means connected to said winding to divide the potentialA existingthere tron discharge system and means interconnecting the other terminal of said winding to said4 anode electrode to apply the part. oi said modato said elec-4 lation potential of opposite sense tron discharge system.

output circuits and including.

'xed" reference potential, a resistance elementcoupled at one end to said control electrode, amodula` reference potential,

. 15. A pulse regeneratingcircuit arrangement including at least an electron discharge system having at least cathode, grid, and anode electrodes, input terminals coupled to said grid and output terminals coupled to said anode, said regenerating circuit being arranged to produce a pulse in said output circuit in response to a pulse applied to said input circuit, and means to modify said pulses, said means including a transformer having a secondary circuit arranged to derive modulating voltages of opposite sense, a connection between `one end of said secondary circuit arrangement and said grid to apply one of said ,modulating voltages to said input circuit, and connections including a capacitor intercoupling the other end of said secondary circuit-arrangement and said anode to apply the other of said modulating voltages thereto, whereby the effect of said modulation voltages on the timing oi said output pulses is substantially balanced.

16..A pulse regener ting circuit having at least one electron discharge device having a cathode, a grid and an anode, input terminals coupled to said grid and output terminals coupled to said anode, an output pulse being produced at 'said output terminals in response to a pulse applied to said input terminals, means to apply modulating potentials to said pulse regenerating ;circuit to modify said output pulse with respect to -said'applied pulse, said means comprising 'a transformer having a secondary circuit arranged tov derive modulating currents of opposite sense, a resistor coupling one end of Y said secondary circuit to said grid to apply one oi said modulating currents thereto, and a connection between the other end of said secondary circuit to apply the-other of said modulating currents to another portion of said circuit, whereby any deleterious effects of said modulating vpotentials on the regeneration of said pulse is substantially eliminated.

17. A pulse modulator circuit arrangement including an electron discharge device having at least cathode, anode and control electrodes, means to apply a'train oi pulses to be modulated tothe cathode and control electrodes, an inductor connected in series with the cathodeanode electrode path of said device and a source of operating potential, an electron discharge y a resistiveelement connecting said source of operating potential to said further grid, a capacitive element connected between said further grid andsaid cathode, a capacitive component coupling the-anode electrode of said electron discharge device to the control grid of said electron discharge system, a resistive component coupled between thecontrol grid and the cathode of said electron discharge system, the resistance value of' said component determining the time delay betweenl application of pulses to said grid electrode of `said electron discharge device and the production of corresponding pulses at the anode of said velectron discharge system, a resistive clement coupled between the control electrode andtheca'thode electrode -of saidelectron discharge device, and a transformer coupled across atleast a part of said resistive element for ap 13 plying modulating potential to said electron dis charge device to Vary the bias thereon and produce a phase shift of pulses at the anode of said electron discharge system proportional to the modulating potential applied to said electron discharge device.

18. A pulse modulator circuit arrangement including an electron discharge device having at least cathode, anode and control electrodes, means to apply a train of pulses to be modulated to the cathode and control electrodes, an inductor connected in series with the cathode-anode electrode path of said device and a source of opi eratng potential, an electron discharge system having at least a cathode, a control grid, a further grid and an anode, a pair of serially connected resistors connected in series with the.

cathode-anode paths of said electron discharge system and a source of operating potential, a capacitor connected between the junction of said serially connected resistors and said cathode, a resistive element connecting a positive source of potential to said further grid, a capacitive element connected between said further grid and said cathode, a capacitive component coupling the anode electrode of said electron discharge device to the control grid of said electron discharge system, a resistive component coupled between the control grid and the cathode of said electronrdischarge system, the resistance Value of said component determining the time delay between application ofy pulses to said grid electrode of said electron discharge device and the production of corresponding pulses at the anode of said electron discharge system, a resistive element coupled between the control electrode and the cathode electrode of said electron dis- Y charge device, and a transformer coupled across at least a part of said resistive element for applying modulating potential to'said electron discharge device to vary the bias thereon and produce a phase shift of pulses at the anode of said electron discharge system proportional to the modulating potential applied to said electron discharge device.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,478,919 Hansell Aug. 16, 1949 2,568,099 Townsley Sept. 18, 1951 

